Pavel Pavlovich Demidov, son of Pavel Nikolaevich Demidov and Aurora Karlovna Shernval, was the godson of P. Ya. Ubri, his daughter E. Marchenko, E. M. Frolova-Bagreyeva, and A. N. Demidov. Losing his father at an early age, he received an excellent home education. In 1856, he entered the law faculty of St. Petersburg University, graduating in 1860 with a candidate degree. He then moved to Paris, where he continued his studies under Laboule, Frank, and Baudrillard.

From 1863, Demidov worked as a secretary at the Russian embassy in Paris. During this time, he acquired a villa in Deauville and began construction of a palace on Jean Goujon Street in Paris. In 1865, after being involved in a duel, he was transferred as secretary to Vienna. In January 1866, he was officially appointed.

Life at the court of Emperor Franz Joseph required significant expenses. Demidov's friends, Prince Baryatinsky and Count Tolstoy, often borrowed money from him. In 1865 and 1866, Baryatinsky received almost a million marks from Demidov. These expenses forced Demidov to sell the villa in Deauville and the palace in Paris.

In 1867, Pavel Pavlovich married Princess Maria Elimovna Meshcherskaya, who died a year after giving birth, leaving a son, Elim. The death of his wife was a heavy blow for Demidov, and he became very religious, contemplating conversion to Catholicism. In October 1868, he moved to Paris and established the Mariinsky Handicraft Workshop in memory of his wife.

In 1869, Demidov returned to Russia and settled in Kamyanets-Podilskyi, where he became an advisor to the provincial government. He spent the summer of 1870 in Italy, inheriting from his late uncle A. N. Demidov. In the fall, he returned to Kamyanets-Podilskyi and then moved to Kyiv, where he became an honorary justice of the peace and Kyiv's mayor in 1871.

That same year, Demidov married Princess Elena Petrovna Trubetskaya, and they had six children, including daughter Aurora, the mother of Yugoslav Prince Regent Paul Karađorđević. In September 1872, he resigned as mayor, but in the spring of 1873, he took the position again.

In August 1873, Demidov received the court title of 'in the position of chief forester' and was elected a member of the Kyiv City Duma. However, he refused to run for mayor due to health reasons and moved to St. Petersburg, then to the villa San Donato.

On June 2, 1872, Emperor Alexander II allowed Demidov to use the title of Prince of San Donato and wear Italian orders. In 1873, he purchased the Pratolino estate and began its restoration. During the Russo-Turkish War, Demidov returned to Kyiv and became an extraordinary commissioner from the Red Cross Society, receiving the rank of state councilor and the orders of St. Anna and St. Stanislaus.

In Florence, Demidov opened schools and shelters, organized dining halls for workers. In 1879, he and his wife were awarded a gold medal and became honorary citizens of Florence. In 1880, Demidov left Florence, donating a church to the Orthodox Church and selling his collection at auction. The sale of San Donato was a heavy blow for him.

After the assassination of Alexander II, Demidov became one of the organizers of the secret monarchist organization 'Holy Brotherhood.' In 1883, he participated in the Commission for the Revision of Laws on Jews and wrote a brochure 'The Jewish Question in Russia.' He also founded the first Bessemer steel factory at his plants.

In the last months of his life, Demidov spent time at the Pratolino villa. Feeling better, he went hunting, but his condition worsened. His son Elim arrived on January 14, and on January 17, 1885, Pavel Pavlovich died from a liver abscess. His body was transported to Russia and buried in the Demidov family tomb in Nizhny Tagil.

Shortly before his death, King Umberto I elevated Demidov's children to princely dignity. The eldest son Elim received the title of Prince of San Donato, while the other children received titles of princes and princesses of the Demidovs of San Donato.

According to Bogdanovich's diary, in the early 1880s, Demidov became close to Ekaterina Vasilyevna Muravyova, who remained with him until his death.

The art objects from the Pratolino villa were sold at auction in 1969, and the villa itself was sold in the province of Florence a year later. After Demidov's death, his Ural factories began to decline, suffering greatly from the crisis of the 1900s. In 1909, the Council of Ministers reported the complete decline of the factories, which had been launched and were heavily indebted. In 1908, the heirs appealed to the government for permission to sell the factories to French industrialists, and the government issued two loans of 750,000 rubles.